A receptor-like flagellar pocket glycoprotein specific to Trypanosoma brucei gambiense

Trypanosoma brucei gambiense and T. b. rhodesiense are protozoan parasites: causing sleeping sickness in humans due to their resistance to lysis by no rmal human serum (NHS). Based on the observation that the resistance gene o f T. b. rhodesiense encodes a truncated form of the variant specific glycop rotein (VSG), we cloned a similar gene in T. b. gambiense using reverse tra nscription-linked polymerase chain reaction with VSG-specific primers. This gene, termed TgsCP for T. gambiense-specific glycoprotein, was found to be specific to T. b. gambiense. It is located close to a telomere and is tran scribed by a pol II RNA polymerase, only at the bloodstream stage of the pa rasite development. TgsGP encodes a 47-kDa protein consisting of a N-termin al VSG domain presumably provided with a glycosylphosphatidylinositol (GPI) anchor sequence, similar to the pESAG6 subunit of the trypanosomal transfe rrin receptor. TgsGP is located in the flagellar pocket, and contains the l inear N-linked polyacetyllactosamine characteristic of the endocytotic mach inery of T. brucei. These observations strongly suggest that TgsGP is a T. b. gambiense specific receptor. Since stable expression of this protein in T. b. brucei did not confer resistance to NHS, TgsGP may either need anothe r factor to achieve this purpose or fulfils another function linked to adap tation of the parasite to man. (C) 2001 Elsevier Science B.V. All rights re served.